The cirripede fauna of the island of Trinidad has been little investigated. SOUTHWARD (1962) recorded five species collected in north-west Trinidad for experimental studies; he listed Chthamalus fragilis Darwin on mangroves, Balanus amphitrite var. on mangroves and harbour piles, B. tintinnabulum Linnaeus on piles and Tetraclita radiata Blainville and T. squamosa Bruguiere on rocks. The determinations for all these species have been revised recently (SOUTHWARD, 1975). Specimens of Newmanella radiata Blainville from the collections described below were included by Ross (1969) in his revision of the genus Tetraclita. A provisional list of the Trinidad cirripedes was given in an appendix to a report on a local swamp (BACON, 1970a) and reports have also been published on the fouling of mangrove oysters by barnacles (BACON, 1970b), barnacles commensal on leatherback turtles nesting in Trinidad (BACON, 1970c), the seasonal occurrence of cirripede larvae in local estuarine plankton (BACON, 1971a) and the ecology of B. eburneus Gould in a west coast mangrove area (BACON, 1971b). Barnacles from the mangrove areas assigned provisionally in these reports to “B. amphitrite” and “C. fragilis” required further taxonomic study.